I don't understand what you are saying here. Why would it be political suicide. Drive more = pay more. Plenty of people who live in these counties and use public transport to get to work would be delighted. Why should they subsidise those who want to drive to Dublin, which is the most accessible via public transport anyway? Who could have an issue with that?
And why would an increase in the cost of motor fuel (offset by the abolition of flat rate motor tax) affect the cost of houses in the suburbs.
Anyway, Minister Gormley himself has effectively said that it won't be enforced by using the magic term "gardaí will use their discretion"
http://www.rte.ie/news/2010/0826/motor_tax.html